Phonograph



Jan. 29,193.5.`

PHONOGRAPH Filed Sept. 21, 1935 /N VENTO/e C har/es -/uen lic/z ATTORNEYPatented Jan. 29, 1935 I I UNITED STATES PHONOGRAPH Charles Huenlich,Bloomfield, N. J., assignor to Thomas A. Edison, Incorporated, WestOrange, N. J., a corporation of New Jersey Application September 21,1933, Serial No. 690,368 u 22 Claims. (Cl. 274-29) My invention relatesto business phonographs or dictating machines and is more particularlydirected to the sound recording and reproducing instruments employed inthese machines. Such ,5 machines are adapted to record upon a waxcylinder the voice of the speaker or dictator and to reproduce therecorded matter. The recording on the cylinder is accomplished bymeansof a suitable stylus or cutting tool bearing on the cylinder andconnected to a vibratory diaphragm which is supported or mounted in asound box. The sound box is connected to a speaking tube sothat thediaphragm is caused to vibrate in accordance with` sounds spoken intothe tube. The vibrations of the diaphragm are transmitted to the stylusandfin consequence engrave a groove oflvarying depth upon the surface ofthe record tablet when the latter is rotated.

In such machines the sound box is usually pivotally mounted and thestylus bears against the record tablet with a pressure determined by themass of the sound box and the relative position of the stylus and thesound box pivot. When the record tablet is rotated the stylus cuts intothe material of the tablet and a force is generated against the styluswhich tends to move the stylus out of the wax. The stylus will thereforesink into the wax until the force tending to move it outis equal to theforce tending to press it into the Wax and an equilibrium is therebycreated. 'Such a. structure therefore tends to cut a groove of uniformdepth in the record tablet.

In such devices there is a certain minimum of weight which can beobtained in the sound box if the construction is to have reasonablestrength. This fact has in the past definitely limited the minimum depthof groove which could be obtained with such a recorder. However, from aconsideration of the frequency characteristics of such 40 recorders, itis desirable to have the mass of the sound box frame as high as possiblein order to provide sufficient inertia to prevent vibration of the soundbox frame with the diaphragm. The greater the mass of the sound boxframe, the farther into thelow frequency part ofthe frequency band it ispossible to record.

In the past it has been found extremely undesirable to make the soundbox any heavier than could be avoided by good design in order that thedepth of groove cut by the stylus might be as small as possible. It isdesirable to keep the depth of groove small to avoid tearing of therecord material by the stylus. It is also well known in the art that themore shallow the record groove 55 produced by the recorder, the lowerwill be the surface noise accompanying the reproduction. We thereforehave two sets of conditions which indicate entirely different designs.From the standpoint of stability and frequency characteristics it isdesirable to provide a sound box frame having a large mass. `On theother hand, considerations of surface noise and accuracy of engravingrecommend a minimum pressure on the rec'- ord.

It has been suggested that a counterbalancing weight be applied to thesound box to overcome these diiiiculties. Such a counterbalancing weightwould have the advantage of increasing the inertia of the sound boxwhile simultaneously decreasing the effective pressure of the recordingstylus upon the record tablet. Such a counterbalance would thereforealso have the advantages of extending -the frequency response of therecorder, of decreasing the depth of groove and thereby the surfacenoise produced, and of rendering the sound box more stable and lesslikely to be moved out of its normal or proper operative position.

However, if a simple counterbalance is applied to such a recorder, newproblems are encountered. If the counterbalance should be allowed toextend beyond the conflnes of the enclosing casing for the sound box, itmight be accidentally touched or moved during recording with thepossible results of spoiling a record and breaking the recording stylus.If, on the other hand, the enclosing casing for the sound box should beextended to cover such a counterbalance, it would render the assemblytoo large and cumbersome. Such a structure would tend to destroy thevisibility of the record which is highly desirable, and would tend totake up too much space on machines of the type for which it would bedesigned, which machines should in general be as compact and neat aspossible.

The principal object of my invention therefore is to provide an improvedand novel construction for counterbalancing the part of and preferablythe greater part of the weight of the diaphragm assembly duringrecording so that the groove cut on the record surface can be be madeshallower, and more accurate and uniform, and will be less apt to beaffected by irregularities or impurities in the record material.

Another object is to provide a. more effective counterbalancing of thediaphragm assembly so as to increase the frequency range of recordingand the uniformity of recording over the entire range.

A further object of my invention is to provid a counterbalance structurehaving the above gbl characteristics and which is adapted to be fullyenclosed within the sound box casing so as to be` protected againstaccidental upset or misadjustment. j

A still further object of my invention is to provide an improvedcounterbalance structure which may be readily adjusted to differenteiective values without changing the relative position of the parts ofthe sound box.

Other objects and features of my invention will be disclosed in thefollowing specification and the appended claims.

For a. clearer understanding of my invention, attention is directed tothe drawing accompanying and forming part of this specication, wherein;

Figure l is an elevational view, partly in sec- I tion, of a combinedphonographic recorder and reproducer assembly embodying my invention,the mechanism being shown as conditioned for recording;

Fig. 2 is an elevational view, partly in section of the combinedrecorder and reproducer assembly of Fig. 1 when it is conditioned forreproducing.

Fig. 3 is a plan view of they counterbalancing mechanism of therecorder;

Fig. 4 is a bottom plan view of the combined recorder and reproducershown in Fig. 1; and

Fig. 5 is a sectional view taken approximately on the line 5-5 of Fig.2.

The combined recorder and reproducer comprises a cup-shaped member 2which acts as a frame for supporting the mechanism and which is designedto fit into a carriage 1 adapted to be moved transversely of a recordtablet A as the latter is rotated. The sound box 4 comprises a circularchamber supporting a diaphragm 5 which is held in place by a gasket 5 ofsoft material. A stirrup 6 is secured to the diaphragm 5 and carries atits outer end a recording stylus '7. I'he sound box 4 is pivotallysecured concentric with the cup 2 by a mounting bracket suitablysecured, as by sweating or spot welding, to the sound box casing andcomprising a pair of spring arms 4' properly drilled at their outer endsto receive the conical ends of a short pivot shaft 16, which is mountedin the bifurcated end 3 of a lug 3 depending from cup 2. A partiallythreaded screw 15 is provided to adjust the tension on the pivots. 'I'hetop portion of the chamber 4 comprises a centrally drilled sphericalboss 8 adapted to coact with the internal spherical end of a tube 9thereby forming a universal joint` The tube 9 extends upwardly into aneck l0 fo`rmed on the frame 2 and thereby connects the sound box 4 to aspeaking tube (not shown) adapted to lit over the neck 10. A suitablyformed wire retaining member 11 is used to hold the tube in place on thesound box 4.

In the slot 3 of the bifurcated end of lug 3 a bracket 1'7 is pivotallymounted on the center portion of shaft 16. A floating weight 12 ispivotally mounted for transverse movement on the bracket 17 by ashouldered screw 18 passing through a boss 18 on the floating weight. Astylus arm 13 is pivotally mounted in the oating weight l2 by a pin 13and carries a reproducing stylus 14 at its outer end. The end of the arm13 opposite to that which carries the stylus is positioned at all timeswithin the stirrup 6. The floating weight is provided with a centralhole through which the stirrup 6 and recording stylus '7 may freelypass. An advance ball 19, preferably made of sapphire and having aspherical end portion for engagement with the record tablet is mountedon the floating weight.

A forked member 2l is pivotally mounted at one end about the center ofthe screw 15. At its other end the forked member 21 is pivotallyconnected to a pair of arms 22 turned up from an extension 25 of anannulus 25. A pin 23 secured in a block 24 which is fastened to theinner top portion of thecup 2 passes through the arms 22 and provides apivotal mounting for the annulus 25. The annulus 25 encircles the tube9. An adjustable weight comprising an annular member 26 is can'ied bythe annulus 25. The member 26 is partially cut away and is providedaround its periphery with a groove adapted to fit into the inner side ofthe annulus 25. The member 26 may be assembled to the annulus 25 byspringing it inwardly until it will pass inside of the annulus 25.

When the apparatus is to be used for recording, both the sound box 4 andthe floating weight 12 are allowed to swing downwardly until they takeup the position shown in Fig.. l in which the recording stylus 'lengages the record tablet and in which the floating weight 12 is carriedon the record tablet by reason of the contact of the advance ball 19therewith. It will be noted that the advance ball 19 -is positionedslightly in advance of the recording stylus so that as the record tabletis revolved and a groove is cut by the recording stylus, the advanceball will ride over the uncut portion of the record tablet in advance ofthe recording stylus. The iloating weight has no part in the process ofrecording, the advance ball being used as a convenient means of carryingthe oating weight in a position in which it does not interfere with theoperation of recording. By reason of the pivotal connection of thecounterbalance 26 with the sound box 4 it\will bei noted that wheneverthe sound box is moved upwardly, the counterbalancing weight 26 is moveddownwardly and vice versa.

It will therefore be seen that the weight 26 acts as a counterbalance tothe sound box and will reduce the effective downward pressure on thestylus, thus reducing the depth of groove as compared with that whichwould be obtained without the use of the counterbalance and at the sametime increasing the inertia of the sound box assembly. Such use of thecounterbalance as has been explained hereinbefore increases the range ofresponse of the recorder, renders it more stable, and results in asmaller amount of surface noise in recording. It will be noted that bythis construction the counterbalance is located entirely within the cup2 and also wholly within the space which would be enclosed by a verticalsurface defining the periphery of the sound box 4. The recordermechanism is thus entirely protected and it is impossible toaccidentally touch or otherwise disturb the mechanism during recording.This construction also renders Athe combined recorder and reproducerassembly very compact and does not increase its size appreciablyoverthat which is now in common use in dictating machines so that easyreplacement of existing recorders is made poible.

Since a portion of the annular weght 26 is cut away, the eect producedby the counterbalance may be readily varied by turning this weight onthe annulus 25. A considerable change in the magnitude of the effectiveweight of the recorder assembly may be obtained in the manner since theeffective center of gravity of the weight 26 is shifted considerably byshifting its position; However such shift involves no chang in therelative positioning of the Various parts of the combined recorder andreproducer assembly and forms a convenientmeans of making thisadjustment without taking up excessive space.

When it is desired to condition the combined recorder and reproducerassembly for reproduc-` therefore moves downwardly until it reaches therecord. In this case the oating weight in which the reproducing stylusarm 13 is fulcrumed is held clear of lthe record and serves to bias thereproducer arm into engagement with the record groove for reproductionin the well known manner. By the construction explained above, I haveprovided a combined recorder and reproducer assembly in which theeffective pressure on the recording stylus is counterbalanced duringrecording, the entire structure taking up very little more space than isnow normally required in commercial combined recorder and reproducerassemblies not having this counterbalancing feature with its attendantadvantages.

Having thus described my invention, I claim:

1. A sound box having a stylus. arranged to cut a groove on a recordtablet of a depth proportional to the effective weight of said soundbox, and a counterbalance for said sound box comprising a movable weightlocated above and within the space which would be enclosed by a verticalsurface defining the periphery of the sound box.

2. A sound box having a stylus arranged to cut a groove on a recordtablet of a depth proportional to the effective weight of said soundbox, and a counterbalance for said sound box comprising a pivoted weightlocated above and within the space which would be enclosed by a verticalsurface defining the periphery of the sound box.

3. A sound box having a stylus arranged to cut a groove on a recordtablet of a depth proportional to the effective weight of said soundbox, afulcrum for said sound box, and a counterbalance for said soundbox located on the same side of said fulcrum as said sound box.

4. A sound box having a stylus arranged to cut a groove on a recordtablet-of a depth proportional to the effective weight of said soundbox, a fulcrum for said sound box, a pivotally mounted counterbalancefor said sound box located on the same side of said fulcrum as saidsound box, and al connection between said sound box and saidcounterbalance.

5. A sound box having a stylus arranged to cut a groove on a recordtablet of a depth proportional to the effective weight of said soundbox, a fulcrum for said sound box, and counterbalance for said sound boxlocated above said sound box and on the salme side of said fulcrum assaid sound box.

6. A sound box having a stylus arranged to cut a groove on a recordtablet of a depth proportional to the eiective weight of said sound box,a frame for said sound box, and a counterbalance for said sound boxlocated within said frame.

positioned on the same side ot said pivotal mounting as said sound box.

8. A sound box having a stylus arranged to cutl a groove on a recordVtablet of a depth proportional to the effective weight of said soundbox, and a counterbalance for said sound box, said counterbalance beingadjustable to change its eiective weight without translatory change ofits postion in a lateral direction relative to said sound box.

9. A sound box having a stylus arranged to cut a groove on a recordtablet of a. depth proportional to the effective weight of said soundbox, and an adjustable counterbalance for said sound box located aboveand within the space which would be enclosed by a vertical surfacedenning the periphery of said sound box.

10. A sound box having a stylus arranged to cut a groove on a recordtablet of a depth proportional to the effective weight of said soundbox, a fulcrum for said sound box, and an adjustable counterbalance forsaid sound box located on the same side of said fulcrum as said soundbox.

11. A sound box having a stylus arranged to cut a groove on a recordtablet of a depth proportional to the eiective weight of said sound box,and a counterbalance for said sound box located above said sound box,said counterbalance being adjustable to change its eect withouttranslatory change of its position in a lateral direction relative tosaid sound box.

12. A sound box having a stylus arranged to cut a groove on a recordtablet of a depth proportional to the effective weight of said soundbox, and a counterbalance for said sound box comprising a memberrotatable to a plurality of positions, said member having unequal weightdistribution with respect to its axis of rotation to change theeffective value of said counterbalance.

13. A combined recorder and reproducer assembly 4comprising a sound boxhaving a stylus arranged to cut a groove on a record tablet of a depthproportional to the effective weight of said sound box, and acounterbalance for said sound box comprising a movable weight locatedabove and within the space which would be enclosed by a vertical surfacedening the periphery of said sound box.

14. A combined recorder and reproducer assembly comprising a sound boxhaving a stylus arranged to cut a groove on a record tablet of a .depthyproportional to the eiective weight of said sound box, a fulcrum forsaid sound box, and a counterbalance for said sound box located on thesame side of said fulcrum as said sound box.

15. A combined recorder and'reproducer assembly comprising a sound boxhaving a stylus arranged to out a groove on a record tablet of a depthproportional tothe effective weight of said sound box, and acounterbalance for said sound box locatedv above said sound box, saidcounterbalance being adjustable to change its effect without translatorychange of its position in a lateral direction relative to said soundbox.

16. A combined recorder and reproducer assembly comprising a frame, asound box pivotally mounted on said frame and having a stylus arrangedto cut a groove on a record tablet of a depth proportional to theeffective weight of said sound box, a counterbalance pivotally mountedon said frame and within the space which would be enclosed by' avertical surface dening the periphery of said, sound box, and aconnection between said sound box and said counterbalance.

1'7. A combined recorder and reproducer assembly comprising a frame, asound box pivotally mounted on said -frame and having a stylus arrangedto cut a groove` ona record tablet of a depth proportional to theeilective weight of said sound box, a counterbalance pivotally mountedon said frame above and within the space which would be enclosed by avertical surface defining the periphery of said sound box, and aconnection between said sound box and said counterbalance.

18. A combined recorder and reproducer assembly comprising a frame, asound box mounted on a pivot on said frame and having a stylus arrangedtoA cut a groove on a. record tablet proportional to the eiective weightof said sound box, a weight pivotally mounted on said frame abovesaid'sound box; and an opposing angular movement connection between saidweight and sald sound box.

19. A combined recorder and reproducer assembly comprising a sound boxhaving a stylus arranged to cut a groove on a record tablet of a depthproportional to the effective weight of said sound box, a frameenclosing at least a portion of said sound box and having a pivotalmounting for said sound box, and a counterbalance for said sound boxpivotally mounted on said frame and entirely enclosed thereby.

20. A device of the character described comprising a sound box,a`recording stylus and a reproducing stylus associated with said soundbox and adapted to be-alternatively conditioned for operation on arecord tablet, and a counterbalance for said sound box, saidcounterbalance being effective only when the recording stylus isconditioned for operation.

21. A sound box having a. stylus arranged to cut a groove on arecordtabletof a depth proportional to the effective weight of said sound box,a tubular member connected with said sound box, and a counterbalance forsaid sound box comprising a movable weight through which said tubularmember extends.

22. A sound box having a stylus arranged to cut a groove on a recordtablet of a depth proportional to the effective weight of said soundbox, a tubular member connected with said sound box, and acounterbalance for said sound box comprising an annular weight locatedabove the sound box, said weight being mounted `for movement towards andaway from the sound box and said tubular member extending through saidweight.

CHARLES HUENLICH.

